Pipe joints are used to join pipes together in piping systems such as refrigerant piping for refrigeration devices, hot-water supply piping for water heating devices, and water supply piping. In such a case, pipes to be connected need to be inserted to predetermined positions in a pipe joint. Accordingly, a step may be formed in a pipe insertion port of a pipe joint, into which a pipe to be joined is inserted. When the distal end of the pipe is inserted into the pipe insertion port and contacts the step, the structure allows a worker to sense the contact through noise or tactile sensation through the worker's hand.
For example, Patent Document 1 discloses such a conventional bite-in type pipe joint. FIG. 10 illustrates the bite-in type pipe joint. As shown in FIG. 10, a joint body 110 has an external thread cylinder 112, and an external thread portion 111 is formed on the outer circumference of the external thread cylinder 112 to be screwed to a coupling member 120. In the center of the external thread cylinder 112, a pipe insertion port 113 and a communication hole 114 continuous to the port 113 are formed. A step 115 is formed at the boundary between the pipe insertion port 113 and the communication hole 114. The step 115 functions as a restricting portion that restricts the position of the distal end of a pipe 100 to be connected. A cam surface 116 is formed at the entrance of the pipe insertion port 113.
The coupling member 120 has an internal thread cylinder 122, and an internal thread portion 121 is formed on the inner circumference of the internal thread cylinder 122 to be screwed to the external thread portion 111. A pipe through hole 124 is formed in the center of a side wall 123 of the internal thread cylinder 122. A pressing surface 125 is formed on the inner surface of the internal thread cylinder 122. A ferrule 130 is located inside the internal thread cylinder 122. The ferrule 30 is integrally coupled to the side wall 123 of the internal thread cylinder 122 with a thin portion 126 extending in the radial direction.
The ferrule 130 has a pipe insertion hole 131 at its center and a notch 132 in a front portion. The notch 132 is formed by cutting in the inner circumferential surface of the pipe insertion hole 131 radially toward the outside. The rear corner (on the right as viewed in the drawing) of the notch 132 forms an edge portion 133, which is caused to bite into a pipe to be connected. A distal end portion 134 located in front of the notch 132 (on the left side as viewed in the drawing) is inserted like a wedge into the space between the pipe 100 to be connected and the pipe insertion port 113 at the initial stage of fastening, thereby temporarily retaining the pipe 100.
Typically, when connecting pipes using the bite-in type pipe joint described above, an end of a pipe 100 is inserted into the joint body 110 until the end contacts the step 115 as shown in FIG. 10(a). Thereafter, when the coupling member 120 is fastened to the joint body 110 as shown in FIG. 10(b), the rear end of the ferrule 130 is pressed by the pressing surface 125 of the internal thread cylinder 122, so that the edge portion 133 of the ferrule 130 is caused to bite into the pipe to be connected.